Radio Frequency IDentification (RFID) is a method of storing and remotely retrieving data using devices called RFID tags. An RFID tag is a small object that can be attached to a product, animal, or person. RFID tags receive and respond to radio-frequency queries from an RFID reader. RFID tags can be either active or passive. Passive tags require no internal power source, whereas active RFID tags have an internal power source, and typically have longer range and larger memories than passive tags.
An RFID system includes several components including mobile tags, tag readers, and application software. The RFID system enables a query to be received by the mobile tag and the tag responds with data. The data is received by an RFID reader and processed according to the needs of a particular application. The data transmitted by the tag may provide identification or location information, or specifics about the product tagged, such as price, color, date of purchase.
RF identification (RFID) systems are used to track objects, animals and/or people in a large range of applications. As an example, RFID is used to track books in a library. Security gates includes an RF transceiver as part of the RFID reader which detects whether or not a book has been properly checked out of the library. When the book returns, the tag attached to the book is detected and an appropriate record is updated in the library system. In another application, RFID readers previously located in a warehouse are used to identify certain objects (for example, on a track entering the warehouse), or to find the location of certain objects, by communicating with their tags and measuring the position of their tags.
A RFID system employs tags on various objects and readers of the tags in a given space. The main function of an RFID is to enable identifying the objects and possibly reading and writing data of the objects to and from the respective tags. Often the RFID system allows tracking the location of the objects via the respective tag location.
Ultra-wide band communications is particularly useful for determining distance and location of RFID tags. PCT International Patent Application Publication No. WO 2003/098528, (PCT Patent Application No. PCT/IL2003/00358), entitled “Method and system for distance determination of RF tags” is incorporated by reference for all purposes as if fully set forth herein. PCT/IL2003/00358 discloses an RFID system having the capability of automatically identifying unknown tags by sending a broadcast interrogation ultra wide-band (UWB) message signal and receiving responses from tags that receive the message signal.
As known in the art of RFID systems, the readers are devices which identify and store the data from the tags. The tags are attached to assets or materiel being managed. A major goal of an RFID system is to allow asset visibility to the organization and improve the organization's efficiency in asset tracking within different processes within the organization. The RFID system is a useful tool to obtain resource and location information for resource management or materiel management applications such as computer resource management (CRM) or Enterprise Resource Planning (ERP) applications running on interconnected computers within the organization. Typically the readers of the RFID system collect data originating in the tags, communicate and transfer the data with the resource management applications.
An RFID system 10 of the prior art is shown in FIG. 1 including readers 101 communicating with tags 103. Readers 101 are optionally connected to a conventional data switch 100 using Ethernet (e.g. 100BaseT) connections 105. RFID system 10 employing wide-band transmission can cover only limited areas, of typical dimension no more than several hundred meters. This is particularly the case for a RFID system employing ultra-wide band (UWB) communications networks using impulse transmission or otherwise complying with the definition of ultra wide (UWB) as approved by the FCC, or other wide-band communication methods.
Wide-band, low data rate systems (including RFID systems) fall under the category of personal area networks (PAN) and cover a limited area. In some cases, the low data rate systems include several readers that are used to cover the area, whereas tags 103 within this area can communicate with one or more readers 101 within the area. Information regarding tagged objects may be relayed between different RFID cells, according to the prior art from readers 101 through switch 100 to a wide area network such as the Internet to a network operations center (not shown).
In numerous cases, there exists a need to cover a wide area in which assets or objects may move. Due to the limited coverage capability of an RFID system employing UWB, other communications systems are required to achieve the coverage over the wide area. A conventional method for covering a wide area is disclosed in US application 20040203377 entitled, “Communication system for dynamic management of a plurality of objects and method therefor”. In US patent application publication 20040203377, the objects are located within a large coverage area, and communicate their information to a central server. The objects may belong to dynamic groups controlled by group controllers. Another representative prior art reference is US patent application publication 2005/0248454 entitled “Marine Asset Security and Tracking System” as disclosed by Hanson et. al. Hanson et. al disclose a system using radio frequency identification (RFID) tags installed on containers. Multiple RFID readers are required, e.g. on ship, which relay information from the RFID tags to a site server installed on ship or in port. The site server relays information regarding the monitored containers via satellite link to a network operations center (NOC).
However, in many cases a central server or network operations center is not readily available either due to lack of worldwide coverage or insufficient capacity. In other cases, such as when the connection to a network operations center (NOC) requires the use of low earth orbit (LEO) satellites the satellite communication connection is very expensive.
There is thus a need for, and it would be highly advantageous to have a wide area dynamic RFID system using UWB which does not always require the use of a central server nor a network operations center (NOC) for communicating between one RFID/UWB cell to another RFID/UWB cell.
Other Prior Art:
US patent application publication 20050208892, Kotola et al., entitled “System and Method for remote service operation”, provides techniques for the management of information regarding remote services. A remote service link is received across a short-range wireless communications network. The remote services may provide location-specific information regarding topics, such as weather forecasts, local dining and shopping, maps, transit schedules, etc. A mobile device may store and display information that allows a user to initiate service sessions with various remote service providers.
US patent application publication, 20050198208, S. Nystrom, “Accessing data in a short-range wireless communication network” describes a short-range communication system, including a transponder and mobile reader device that integrates information stored on a short range communications tag with information stored remotely at an external network resource. The user of a reader-associated device can access information stored on a short-range communication tag and information stored remotely at a network resource without incurring unnecessary delay. The system of US20050198208 includes a short-range wireless communication tag. The tag includes short-range wireless communication circuitry and a memory unit in communication with the circuitry. The memory unit stores local content information, e.g. Internet home page, and commands for concurrently effecting retrieval of supplemental content information, associated with the local content information from a remote network resource while the local content information is accessible to a remote wireless device.